1. Field of the Invention
The present invention relates to a sealing structure in which an MEA is sandwiched by gaskets integrally provided on separators arranged at both sides of the MEA via GDLs, in a fuel cell.
2. Description of the Conventional Art
There has been known a fuel cell structured such that a membrane electrode assembly (MEA) provided with a pair of electrode layers on both surfaces of a reaction membrane, porous first and second gas diffusion layers (GDL) laminated on both sides thereof in a thickness direction, and separators made of carbon or a metal are alternately arrange and laminate, and fuel gas or oxidation gas is circulated to the MEA via the first and second GDLs. In other words, the fuel cell is structured such as to generate electric power on the basis of an electrochemical reaction corresponding to a reverse reaction to a water electrolytic process, that is, a reaction for creating water from hydrogen and oxygen.
In this kind of fuel cell, it is necessary to seal the fuel gas, the oxidation gas, the water created by the reaction, the surplus oxidation gas, a refrigerant and the like, and a gasket for this purpose is provided. There has been known a gasket which is made of rubber or a synthetic resin material having rubber-like elasticity, is integrally provided on a surface of the separator, and is brought into close contact with the surface of the MEA.
FIG. 7 is a partial sectional view showing a sealing structure of a fuel cell in accordance with a conventional art in a separation state, and FIG. 8 is a partial sectional view showing it in a lamination state.
The fuel cell shown in FIG. 7 is structured such that first GDLs 102 and 103, second GDLs 104 and 105, and separators 106 and 107 are laminated in order on both sides in a thickness direction of an MEA 101 which is provided with a pair of electrode layers on both surfaces of a reaction membrane (an ion exchange membrane), and the MEA 101 or a reinforcing frame integrated with the MEA 101 is sandwiched by gaskets 108 and 109 which are integrally provided on the separators 106 and 107 respectively positioned at both sides thereof in the thickness direction and are made of rubber or a synthetic resin material having rubber-like elasticity, at an outer side of the first GDLs 102 and 103 and the second GDLs 104 and 105 (refer, for example, to Japanese Unexamined Patent Publication No. 2008-34383).
However, in the conventional sealing structure mentioned above, in the lamination state shown in FIG. 8, since a space S is formed between seal protrusions 108a and 109a in the gaskets 108 and 109, and the first GDLs 102 and 103 and the second GDLs 104 and 105, there is a risk that deformation of the MEA 101 is caused in this space S, and there is fear that the MEA 101 is broken at worst. Further, shift of the first GDLs 102 and 103 tends to be caused due to the existence of the space S.